Knowledge of the three-dimensional atomic structure of molecules is essential in understanding their function as well as in designing new industrial pharmaceutical and agricultural materials. A number of existing methods of determining molecular structure are based on x-ray diffraction methods that determine both the amplitude and the phase of the diffraction. They all study the structure of 3 dimensional crystals composed of the molecules of interest and yield good results. The main difficulty with these methods is the need to crystallize the molecules into a 3 dimensional crystal. The process of crystallization is molecule specific, namely, the conditions needed to crystallize different molecules are different and the right conditions for crystallization need to be determined for each type of molecule individually. Many molecules in particular those residing in cell membranes are very difficult or impossible to crystallize at present.
The structures of molecules crystallized as two dimensional crystals have also been studied by transmission electron microscopy. This method provides a quite limited resolution on the order of a few angstroms and, as in all of the other prior art methods, the process of crystallization is the bottle-neck for the investigation of the molecular structure because it is molecule specific. In fact there exist many molecules of interest for which a method of crystallization has not been perfected. Crystallizing a molecule is usually the most difficult part of the structure determination procedure and, therefore, it would be highly desirable if a method could be provided for determining the three-dimensional structure of large molecules, such as biological or chemical molecules, that avoids the necessity of crystallizing the molecules.
It is therefore an object of the present invention to provide a method for determining the three-dimensional atomic structure of large molecules such as biological or chemical molecules.
It is another object of the present invention to provide a method for determining the three-dimensional atomic structure of large molecules such as biological or chemical molecules without the need of crystallizing the molecules.
Further purposes and advantages of this invention will appear as the description proceeds.